Cross groove constant velocity ratio universal joints

Abstract

A cross groove type of constant velocity ratio universal joint, comprising an outer joint member (1), an inner joint member (2), and a cage (3) constraining torque transmitting balls (4) received one in each pair of facing grooves (8, 14) in the outer and inner joint members, the grooves being inclined to the axes of the joint members so as to cross one another, wherein the cage is of asymmetrical configuration, comprising at one end an opening of a diameter greater than an outside diameter of the inner joint member, and at its other end and opening of a diameter smaller than the outside diameter of the inner joint member. The external surface of the cage comprises a number of surface portions (S1 to S5) of different configuration from one another. The configuration of the cage facilitates assembly of the joint and also permits an extended range of plunging movement in one direction, while limiting plunging movement in the opposite direction.

We claim: 
     
       1. A cross groove constant velocity ratio universal joint, comprising: an outer joint member;   an inner joint member;   the inner and outer joint members having circumferentially disposed axially extending facing pairs of grooves, the grooves of each pair being oppositely inclined to the rotational axes of their joint members so that they cross one another as viewed in a direction transverse to said axes;   a plurality of balls disposed one in each facing pair of grooves, for torque transmission between the joint members;   and a cage of annular form disposed between the joint members, the cage having apertures wherein the balls are received to constrain the balls such that their centers occupy a ball center plane;   wherein, as viewed in longitudinal section, the cage is asymmetrical and has at one end an opening of a diameter greater than a maximum diameter of the inner joint member, and at its other end has an opening of a diameter smaller than said maximum diameter of the inner joint member, so that the cage can be fitted axially over the inner joint member from said one end thereof, and said other end of the cage forms a stop for limiting relative axial movement between the cage and inner joint member, the external surface of the cage comprising a number of longitudinally extending portions of different configuration from one another, the portions including a first portion, towards the end of the cage having the larger diameter opening, and a further portion towards the end of the cage having the smaller diameter opening, both of which portions are convex surfaces of revolutions about the longitudinal axis of the cage and which, as viewed in longitudinal section of the cage, having centers of curvature which lie in the ball center plane but which are offset from said cage axis, the first portion having a radius of curvature greater than that of the further portion.   
     
     
       2. A universal joint according to claim 1 wherein the external surface of the cage further comprises a part-spherical portion in the region of the apertures of the cage. 
     
     
       3. A universal joint according to claim 2 wherein the external surface of the cage includes a transition portion between said part-spherical surface portion thereof and the first said convex surface portion thereof, said transmission portion being either a frusto conical surface portion tangential to said part-spherical surface portion, or a surface of rotation about the axis of the cage which is concave as viewed in longitudinal section of the cage. 
     
     
       4. A universal joint according to claim 2 wherein the radius of curvature of said part-spherical surface portion lies between the radii of curvature of said first and further convex surface portions, and the centre of curvature of said part-spherical surface portion lies in the ball centre plane. 
     
     
       5. A universal joint according to claim 4 wherein said part-spherical surface portion of the external surface of the cage extends from the ball centre plane towards the end of the cage having the larger opening, by a distance sufficient to subtend approximately half the normal maximum operating angle of the joint at its centre of curvature. 
     
     
       6. A universal joint according to claim 4 wherein the sum of the said radii of curvature, as viewed in longitudinal section of the cage, of said first and further convex surface portions of the cage is substantially equal to or slightly less than twice the radius of curvature of said part-spherical surface portion of the cage. 
     
     
       7. A universal joint according to claim 1 wherein said further convex surface portion of the cage extends from the ball centre plane to subtend at least half the normal maximum operating angle of the joint at its centre of curvature, as viewed in longitudinal section of the cage. 
     
     
       8. A universal joint according to claim 7 wherein said further convex surface portion is followed, towards the end of the cage, by a frusto conical surface portion which tapers at at least half the assembly angle of the joint. 
     
     
       9. A universal joint according to claim 1 wherein the internal surface of the cage comprises a first portion of cylindrical configuration, extending from the end of the cage with the larger opening as far as the boundaries of the apertures in the cage wherein the balls are received, followed by a portion whose configuration approximately follows that of the external surface of the cage to give a substantially constant wall thickness. 
     
     
       10. A universal joint according to claim 9 wherein the internal surface of the cage comprises, adjacent the end of the cage having a smaller opening, a part-spherical portion forming a stop surface. 
     
     
       11. A universal joint according to claim 10 wherein the inner joint member has a corresponding part-spherical stop surface engagable with the said stop surface in the cage. 
     
     
       12. A universal joint according to claim 11 wherein the inner joint member has, at its end opposite the said stop surface, a part-spherical surface having the same radius of curvature as that of said stop surface, but with its centre of curvature offset along the axis of the inner joint member from the centre of curvature of said stop surface. 
     
     
       13. A universal joint according to claim 12, wherein, between said part-spherical surfaces and extending longitudinally thereof, the inner joint member has an external surface which is of a linear sectional configuration. 
     
     
       14. A cross groove constant velocity ratio universal joint, comprising: an outer joint member;   an inner joint member;   the inner and outer joint members having circumferentially disposed axially extending facing pairs of grooves, the grooves of each pair being oppositely inclined to the rotational axes of their joint members so that they cross one another as viewed in a direction transverse to said axes;   a plurality of balls disposed one in each facing pair of grooves, for torque transmission between the joint members;   and a cage of annular form disposed between the joint members, the cage having apertures wherein the balls are received to constrain the balls such that their centers occupy a ball center plane;   wherein, as viewed in longitudinal section, the cage is asymmetrical and has at one end an opening of a diameter greater than a maximum diameter of the inner joint member, and at its other end has an opening of a diameter smaller than said maximum diameter of the inner joint member, so that the cage can be fitted axially over the inner joint member from said one end thereof, and said other end of the cage forms a stop for limiting relative axial movement between the cage and inner joint member, the internal surface of the cage comprising a first portion of cylindrical configuration, extending from the end of the cage with the larger opening as far as the boundaries of the apertures in the cage wherein the balls are received, followed by a portion whose configuration approximately follows that of the external surface of the cage to give a substantially constant wall thickness, and a part-spherical portion provided adjacent the end of the cage having a smaller opening so as to form a stop surface, the inner joint member having a corresponding part-spherical stop surface engageable with the said stop surface in the cage, additionally, the inner joint member being provided, beyond said stop surface thereof, with a generally cylindrical extension in which the ball-receiving grooves are continued, said cylindrical extension having an outside diameter smaller than the diameter of the smaller opening at the adjacent end of the cage.   
     
     
       15. A universal joint according to claim 14, wherein the ball-receiving grooves in said extension of the inner joint member are substantially parallel to the axis thereof. 
     
     
       16. A universal joint according to claim 15 wherein the ball-receiving grooves in the outer joint member extend a certain distance into the interior of the outer joint member from an open end thereof, and between the grooves the outer joint member affords a cylindrical guide surface which extends towards a closed end of the outer joint member by a substantial amount beyond said distance. 
     
     
       17. A cross groove constant velocity ratio universal joint, comprising an outer joint member;   an inner joint member;   the inner and outer joint members having circumferentially disposed axially extending facing pairs of grooves, the grooves of each pair being oppositely inclined to the rotational axes of their joint members so that they cross one another as viewed in a direction transverse to said axes;   a plurality of balls disposed one in each facing pair of grooves, for torque transmission between the joint members;   and a cage of annular form disposed between the joint members, the cage having apertures wherein the balls are received to constrain the balls such that their centres occupy a ball centre plane;   the cage having an asymmetrical internal surface, comprising at one end an opening of a diameter greater than a maximum diameter of the inner joint member, and at its other end an opening of a diameter smaller than said maximum diameter of the inner joint member, so that the cage can be fitted axially over the inner joint member from said one end thereof, and said other end of the cage forms a stop for limiting relative axial movement between the cage and inner joint member;   the cage further having an asymmetrical external surface comprising a number of longitudinally extending portions of different configuration from one another, including a first portion, towards the end of the cage having the larger diameter opening; a further portion towards the end of the cage having the smaller diameter opening, both of which portions are convex surfaces of revolution about the longitudinal axis of the cage and which, as viewed in longitudinal section of the cage, have centres of curvature which lie in the ball centre plane but which are offset from said cage axis, the first portion having a radius of curvature greater than that of the further portion; and a portion in the region of the apertures in the cage, the sum of the radii of curvature of the first and further said convex portions being at most substantially equal to the maximum diameter of said portion in the region of the apertures in the cage.